242 MINERALOGY AND LITHOLOGY, 



List of Figures. 



Plate I. (Frontispiece.) 



A fragment of a crystal of beryl from Grafton, with a scale representing its 

 dimensions in feet — page 67. 



Plate II. 



Fig. I . A thin section of a rock prepared for microscopic examination ; natural 

 size — page 7. 



Fig. 2. Sections of an augite crystal, drawn to illustrate the optical deport- 

 ment of biaxial crystals between crossed Nicol prisms. ia and 2*5, 

 sections in parallel light. 2 ^, a section in light rendered convergent 

 by the removal of the ocular from the microscope — page 15. 



Fig. 3. Magnetite formed by the decomposition of a hornblende crystal, as 

 seen in a section of diorite from a dyke near the Profile house — 

 page 43. X30 



Fig. 4. Magnetite as seen in sections of diabase. 4 and 4 a in diabase from 

 Bemis brook, \b and /\^c from the flume in Lincoln, \d from Con- 

 cord, Vt. — page 42. X 50 



Fig. 5. Product resulting from the decomposition of titanic iron, as seen in a 

 section of metamorphic diorite from Connecticut lake — pages 40 

 and 228. X 35 



Fig. 6. The same in a section of quartz diorite from Hanover — page 41. x 35 



Fig. 7. Titanic iron as seen in a section of diabase from Bethlehem. x 50 



Fig. 8. The base of a macled crystal of staurolite from Charlestown (Jackson). 

 8« the base of one of these crystals as figured by Rosenbusch — 

 page no. 



Fig. 9. Figure illustrating the arrangement of the crystalline axes with refer- 

 ence to one another in the plates of muscovite and biotite, which 

 are frequently found united together at their edges, in the mica 

 quarries — pages 80 and 83. 



Fig. 10. Tourmaline crystals flattened out between folix of mica — page 85. 



Plate III. 



Fig. I. Crystals of arsenopyrite from Franconia (Dana) ; i and i a arsenopy- 



rite ; \ b danaite — page 34. 

 Fig. 2. Crystal of vesuvianite from Amherst (Dana) — page 76. 

 Fig. 3. Crystal of tourmaline from Springfield, showing the peculiar habit of 



the species as there found — page 103. 



